The most common method of drug testing is by testing a urine sample. An employee or applicant provides a sample to be tested. Usually precautions are taken, such as putting blue dye in the toilet and turning off the water supply, to prevent adulteration or substitution of specimens so that collection can be completed in privacy without any direct visual observation by another person.

How long are drugs in one’s system?

Drugs have certain “detection windows”—the amount of time after ingestion during which evidence of their use can be detected by a drug test.

The following are estimates of the length of time that certain drugs are detectable: